What determines the number of political parties in a democracy? Electoral rules certainly influence the incentives to create and maintain parties. However, a society's political culture can maintain parties despite electoral rules that give them poor prospects of success. Thus, comparing the number of parties and differences in electoral rules across countries cannot clearly test the effect of the electoral rules. A better test would examine a society with a fairly continuous political culture, but a change in electoral rules. Postwar France is such a society. While the basic social order has not changed, there was a drastic change in the electoral system in 1958, which theory implies would reduce the number of parties. Thus we can test the hypothesis that the number of parties fell with the change in electoral system. We can also calculate an " equivalent number of parties· to see how closely France approached a two - party system under the new regime. The first section describes the electoral rules under the Fourth and Fifth Republics. The second section develops a model that indicates how the change in electoral rules should have affected the incentives for multiple parties. The third section tests the hypothesis that the number of parties fell from the Fourth to the Fifth Republic. 1. Electoral Rules In the French Fourth Republic (1945 - 1958) political parties existed largely to serve the direct interests of their members.

Inhalt
1 Introduction.- The Logic of Multiparty Systems: An Overview of Theoretical and Empirical Problems and Results.- 2 Efficiency and Stability Concepts in Multiparty Voting.- Bargaining in Weighted Majority Voting Games, With an Application to Portfolio Distributions.- Nash Bargaining Solutions of Multiparty Bargaining Problems.- Manipulation of Voting Mechanisms.- Manipulation in a Multiparty Parliament: The Case of the Norwegian Storting.- On the Existence of Political Equilibrium in a Three-Party System with Plurality Voting.- Elections with N Voters, M Candidates and K Issues.- 3 Multipartism and Political Stability.- Bargaining Theory and Cabinet Stability in European Governments.- Multipartism.- The Competitive Consequences of Polarized Pluralism.- On the Importance of Elections and Ideology for Government Policy in a Multi-Party System.- The Political Economy of Roll-Call Voting in the Multi-Party Congress of the United States.- Parties and Party Systems in Latin America.- The Stability of Party Duopoly in Multi-Party Britain.- The Geography of Party Support: Comparative Studies in Electoral Stability.- 4 Electoral System Effects.- 'Representation of the People': Aspects of the Relationship between Electoral Systems and Party Systems in the Federal Republic of Germany and the United Kingdom.- What Kind of Electoral System for Plural Societies? India as an Example.- Political Support in Multiparty Canada: 198084.- Performance of the Electoral System in Recent Canadian and British Elections: Advancing the Case for Electoral Reform.- The Logic of Plurality Voting in Multi-Party Systems: Tactical Voting in Liverpool Elections.- Determinants of the Number of Legislative Parties: Evidence from Postwar France.- Problems of and Solutions to Representation.-Thresholds for Proportional Representation: Reanalyzed and Extended.- Problems of Equity in Multiparty Representational Systems: What We Want and What We Can't.- Party Discipline and the Power of Parties, Legislators and States.- Paradox Proof Decision Rules in Weighted Voting.